Staple stitchers

ABSTRACT

A stitcher head having a swivel staple support member, driver and driver bar is so constructed that the support member rather than the driver shifts the swivel while the driver bar rather than the driver shifts the support member, thereby unloading the driver to a considerable extent.

United States Patent [1 1 nn Bulka {45} Apr. s, 1975 {5 STAPLE STITCHERS1.983.384 0/1934 McClure 227/90 x 1.531985 ll 95() N1 h .127'90 [75]Inventor: Raymond l. Bulka, Oak Lawn. Ill. H I

[73] Assignee: McCain Manufacturing Corp" Primary ExuminerGranvilie Y.Custer Jr.

Chicago. Ill Attorney. Agent, or FirmKinzer Plyer. Dorn. 22 Filed: Jan.24, 1974 McEmhm 2| A .N ,1 436.210 1 pp 0 57 ABSTRACT A stitcher headhaving a swivel staple support mem' 52 l. S 3;??? ber. driver and driverbur IS so constructed that the 5 V I V 1 V I. 5' support member ratherthan the driver shifts the 8] Field of Seal-(h 90 swivel while thedriver bur rather than the driver shifts {56] References Cited thesupport member. thereby unioading the driver to a considerable extent.UNITED STATES PATENTS 1.301402 4/191; Maynard 227M 4 Claims 9 DrawingFigures STAPLE STITCHERS This invention relates to a stitcher head ofthe kind which feeds. cuts and shapes wire to the form of a staple andthen clinches the staple to the work.

Stitcher heads of the foregoing kind are customarily used to joinsignatures to form a book. A signature is a folded sheet. In formingbooks from signatures. the signatures may be gathered one atop anotheron a socalled saddle conveyor. The signatures so collected are deliveredto the stitcher head where the backs of the signatures are joined bystaples as disclosed in McCain US. Pat. Nos. 3.275.2l0 and 3.542.271.

Known stitcher heads are employed in stitching signatures. The stitcherhead is of the kind disclosed in U.S. Pat. No. l.302.-'l()2. The lengthof wire from which the staple is formed is cut and positioned verticallyin a groove of a swivel which is then turned to dispose the wire lengthin a horizontal position. Afterwards the bender bar shapes the wire toU-form while the wire is held by the swivel. Next. a driver bar carriesa related driver downwardly. The free end of the driver engages theswivel and causes it to be retracted. As the swivel is retracted. itreleases the bent wire to a pivotal support member; the legs of the bentwire are guided by grooves in the bender bar. The driver and supportmember cooperate to square off the crown of the staple. Further descentofthe driver and driver bar is characterized by the end of the driverengaging the support member to move the latter to a retracted positionand at the same time the driver forces the wire into the work to whichthe staple is clinched.

The free end of the driver does a great deal of work in the knownstitcher head: in addition to driving the staple into the work it isresponsible to move both the swivel and the support member to retractedpositions and to cooperate with the support member in squaring off thestaple.

It was mentioned above that the bender bar in the known device hasgrooves for guiding the legs of the shaped wire. These same groovesserve as guides for vertical ribs on the sides of the driver and in factthe ribs on the driver are heavily loaded during descent as will now beexplained.

During high speed operation (e.g.. 250 cycles per minute) using thinwire. frequent unexplained failures of the driver have been encountered.Specifically, the guide ribs shear off. This failure can be traced tosmall but significant forces tending to twist the driver out of avertical plane. Thus. the ribs on the driver are only as thick as thewire being fed. because both the ribs and wire are guided by the groovesin the bender bar. With this in mind, and bearing in mind that thedriver is bound to experience horizontal components of force in oppositedirections as its free end displaces the swivel in one direction and thesupport member in the opposite direction, the reason for failure becomesapparent. namely. for thin wire and at high speeds the thin driver ribsultimately undergo fatigue failure because of the rapid, repeatedtwisting in successive machine cycles. The object of the invention is toavoid this failure and thereby impart prolonged life to the driver. Morespecifically. it is an object of the present invention to remove fromthe driver the work load of displacing the swivel and the support memberand to transfer part of this work to the heavier driver bar so that theonly work of the driver is to cooperate with the support to straightenthe crown of the wire staple and to drive the staple into the work. Yetmore specifically it is an object of the present invention to use thestaple support member to displace the swivel and to extend the free endof the driver bar beyond the free end of the driver so that the driverbar. rather than the driver. will displace the support member.

Other and further objects of the present imention will be apparent fromthe following description and claims and are illustrated in theaccompanying drawing which. by way of illustration. shows a preferredembodiment of the present invention and the principles thereofand whatis now considered to be the best mode contemplated for applying theseprinciples. Other embodiments of the invention embodying the same orequivalent principles may be made as desired by those skilled in the artwithout departing from the present invention.

In the drawing:

FIG. I is a sectional view of a stitcher head constructed in accordancewith the present invention.

FIG. 2 is a detail sectional view of an enlarged scale compared to FIG.I:

FIG. 3 is an end view of the swivel and related parts;

FIG. 4 is an elevation of the staple support member;

FIG. 5 is a view at the underside of the driver and driver bar;

FIGS. 6 and 7 are elevations of a slide; and

FIGS. 8 and 9 are elevations of the driver bar.

The description to follow in many instances repeats parts of thedisclosure in US. Pat. No. 1.301.402. and in fact. some of the samereference characters are employed. sufficient to identify parts oftheknown stitcher head with which the present invention is concerned.

FIG. I shows a section of the bonnet B of a stitcher head conforminggenerally to US. Pat. No. 1.302.402. On the forward end ofa drive shaftS. FIG. I. is a crank 8 carrying a wrist pin 9 through which motion istransmitted to the reciprocating elements in the stitcher head or bonnetB. The reciprocating elements consist essentially of a driving bar D. adriver bar D' connected to be reciprocated therewith. a staple driver Dcarried on the lower end of the driver bar D. and a staple former orbender bar F arranged to reciprocate independently of the other slidingparts. The bender bar F is of rectangular. plate-like construction withsplines or ribs f. FIG. 5, on its opposed vertical edges fitted to slidein corresponding grooves 13, FIG. 1, in the sides of the bonnet B. InFIG. 1 a portion of one side of the bender bar is cut away to reveal thedriver and driver bar.

The driver bar D is mounted to slide in the slotted front face of thebender bar F. FIG. 5, noting that FIG. 5 is a view looking upwardly fromthe bottom of the structure in FIG. 1. The driver bar D' is coupled tothe driving bar D at its upper end. FIG. 1, by a tongue-andgrooveconnection shown at 14.

The driver D is fitted to the front of the driver bar D at its lower endas by a spring clip 10, FIG. 9, fas tened to the forward face of thedriver bar D. the spring clip free end fitting in a pocket (not shown)in the rear face of the driver D The driver D is merely a flat plate ofhardened metal, loosely supported but guided in the manner to bedescribed. The opposite. vertical sides of the driver D are providedwith thin ribs or splines 15, FIG. 2, which slide in correspondinggrooves formed in the sides of a slot in the bender bar F. Partly inthis manner the driver bar D and its connected driver D are held inplace on the front of the bender bar F while being adapted to slide inrelation thereto. Unlike the known construction. however. the guide ribson the driver do not take any load but ser\e merely as guide as will beexplained.

As described in the aforesaid patent. the bender bar F is cut away(bifurcated) at the bottom. forming two parallel. depending legs orextensions 16. FIG. 5. adapted to straddle a cylindrical swivel 17,which is held in a swivel holder I8 on the front of the bonnet B. Theswivel serves as an anvil for shaping the staple when the bender bar isreciprocated downwardly in the guiding grooves 13. The swivel or anvilI7 is arranged to rotate as well as to slide axially in its bearingholder 18 to cooperate with the bender bar F to form the staples in theknown manner.

As described in US. Pat. No. 1.302.402. the swivel at the inner end hasa slot 19 for holding the wire to be bent into the staple. The wirefeeds down through the slot 19 from above. when the swivel is rotated toorient the slot 19 vertically. and a length is severed from the mainlength of wire.

After the wire has been cut off in a length appropriate to the size ofstaple required. the swivel 17 is rotated to bring the severed wire W.FIG. 1. into horizontal position beneath the bender bar F as shown inFIG. 1. As the bender bar descends the ends of its legs 16 will strikethe extended free end portions of the length of wire projecting beyondthe sides of the swivel 17, causing the wire to be bent downwardly toform the opposite parallel legs of the staple ST as shown in FIG. 2.

As the bender bar F continues to descend. after completing the formationof the staple ST. the swivel 17 is forced from its extended or operativeposition to a retracted position as hereinafter described As the swivelor anvil I7 is thus retracted it releases the staple from its cross slot19 (as described in US. Pat. No. 1.302.402) but the legs of the stapleare held in the grooves 15 ofthe bender bar F. FIG. 5. The formed stapleis maintained in this position by a pivotal support member 20 hinged onthe back ofthe bender bar F and having an inclined upper surface 21terminating in a toe 22. FIG. 2. adapted to enter between the legs 16 ofthe bender bar F.

As shown in FIG. 1. the staple support member 20 is provided at its heelwith a pin 23 adapted to ride on the cam face 24C at the underside of acam block 24 when the driver bar has descended to a point where the pin23 is aligned with the cam face 24C. The staple support member is biasedto swing counterclockwise, FIG. 1, by a plunger 25 slidably mounted in abore 26 at the upper end of the support 20 under the influence of aspring 27. The plunger pin 25 bears against the lower end of anotherplunger 28 slidably mounted in a block 29 which operates the bender baras described in US. Pat. No. l.302.402.

After the staple is formed. and while it is being held in the bender barF. with the bottom of the latter pressed against the work. assumed to bea group of signatures SG. FIG. 2, the driver bar D' descends and thedriver D forces the staple down through the work SG in the usual manner.FIG. 2. In accordance with the present invention, the lower free end 30of the driver bar. FIG. 2, is extended beyond the free end of thedriver. Therefore, as the lower end 30 of the driver bar D' comes intocontact with the inclined upper face 21 of the staple support member 20in its operative or advanced position. the driver bar free end 30 forcesthe support 20 back to a retracted position to allow the staple to slideoff the support 20. Thus. the driver bar and not the driver isresponsible for moving the support 20. to its restored or retracted.inoperative position.

After the staple has been driven through the work and set in place forclinching over its ends as described in the aforesaid patent. the benderbar. and shortly thereafter the driver bar. start to ascend. and as theformer moves upwardly the staple supporter 20. in retracted position.travels with it.

It has already been noted that the free end of the driver bar D isextended, compared to the known stitcher. so that the driver bar and notthe driver is re sponsible for camming the support member 20 from itsoperative or advanced. staple supporting position to its released orretracted position. The driver is unloaded to that extent and is furtherunloaded as will now be described The swivel 17, as noted. is arrangedfor axial as well as rotary movement in a swivel holder 18, FIGS. 1 and2. The swivel is biased by a spring means schematically shown at 35,FIG. 1. so as normally to be disposed in an operative position topresent the cut piece of wire W to the descending bender bar. the legs16 of which. FIG. 5. generally shape the wire to U-form. In the knowndevice. the free or lower end of the driver D was responsible forengaging the tapered inner end 36 of the swivel. forcing it to aretracted position at the time the support member 20 shifts to theoperative position shown in FIG. 2 to receive the bent wire from theswivel. This action of the driver, as explained above, contributes todriver failure and is avoided under the present invention by relying onmovement of the support 20 into operative position. toward the swivel.to displace the swivel to its retracted position. In accomplishing this.a slide 38, FIGS. 1 and 2, is supported in the swivel support 18.

The slide 38 has a horizontal leg 39 provided with guide flanges 41,FIG. 7, which fit in corresponding grooves 42G formed within the swivelsupport. The slide has an inner. dependent element in the form of a leg42 in position to be struck by the toe 21 of the staple support member20 and additionally includes an outer. vertically extending leg 43 whichis disposed between the outer end 44 of the swivel support and a cap 45on the outer end of the swivel. Inward movement of the slide is limitedby a stop surface 46 within the swivel support.

When the driver has descended sufficiently to present the pin 23 on thestaple support member to the cam surface 24C, FIG. I, the support memberswings to the right. FIG. 1, and the toe 21 thereof is of sufficientextent to strike the leg 42 of slide 38, shifting the swivel to itsretracted position, FIG. 2, allowing the driver D to clear and freelypass the innermost end of the swivel without striking the swivel. At thesame time. the jaw 19 of the swivel is displaced from the partly shapedstaple ST which drops onto the upper sloped surface of the staplesupport member.

Thus, further loading of the driver D heretofore entailed in shiftingthe swivel. is eliminated, but nonetheless the dimensions are such thatas the driver bar and driver further descend. FIG. 2, the crown of thestaple supported by member 20, is squared off by cooperation between thefree end of the driver D and the staple support 20 concurrently as thefree end 30 of the driver bar engages the support member to shift thelatter clockwise to its retracted position.

When the driver D has cleared the swivel on the return stroke. afteremplacement of the staple in the work 56. the spring means (present inthe known stitcher head) restores the swivel l7 and slide 38.

The brunt of the work of displacing the staple support member. havingbeen transferred to the driver bar D. the latter is provided with sideflanges 47. FlGi 9. which fit in guide grooves 48. P16. 5. formed in thebender bar. As further assurance to relieving the driver D from as muchwork as possible. the ribs 15 on the driver D are so located. to fitgrooves in the bender bar as shown in FIG. 5, that a slight gap isestablished between the opposed surfaces of the driver bar and driver Iclaim:

1. ln 2! wire stitcher head having a swivel for supporting a length ofwire from which a staple is to be shaped by a bender bar reciprocalalong a path normal to the axis of the swivel, and a driver carried on adriver bar for driving the shaped staple into the work. wherein theswivel is to be shifted laterally to clear the path of the driver whileat the same time releasing the shaped wire to a support member pivotallymounted on the bender bar, said support member being moveable toward theswivel to an operative position to receive the shaped wire and beingmoveable away from the swivel to a retracted position. the improvementcomprising: a slide engaging the swivel to shift the swivel laterallyfree of the path of the driver. and said slide having an element in thepath of the support as it moves toward the swivel whereby the support iseffective to laterally shift the swivel when the support engages saidelement,

2. A stitcher head according to claim I further improved in that thedriver bar has an end extended beyond the end of the driver thereby toengage the support in its operative position and shift the support toits retracted position.

3. A stitcher head according to claim 1 further improved in that thesides ofthe driver bar have guide elements fitting grooves in the benderbar.

4. A stitcher head according to claim 3 further improved in that a gapis established between the opposed faces of the driver bar and driver.

1. In a wire stitcher head having a swivel for supporting a length ofwire from which a staple is to be shaped by a bender bar reciprocalalong a path normal to the axis of the swivel, and a driver carried on adriver bar for driving the shaped staple into the work, wherein theswivel is to be shifted laterally to clear the path of the driver whileat the same time releasing the shaped wire to a support member pivotallymounted on the bender bar, said support member being moveable toward theswivel to an operative position to receive the shaped wire and beingmoveable away from the swivel to a retracted position, the improvementcomprising: a slide engaging the swivel to shift the swivel laterallyfree of the path of the driver, and said slide having an element in thepath of the support as it moves toward the swivel whereby the support iseffective to laterally shift the swivel when the support engages saidelement.
 2. A stitcher head according to claim 1 further improved inthat the driver bar has an end extended beyond the end of the driverthereby to engage the support in its operative position and shift thesupport to its retracted position.
 3. A stitcher head according to claim1 further improved in that the sides of the driver bar have guideelements fitting grooves in the bender bar.
 4. A stitcher head accordingto claim 3 further improved in that a gap is established between theopposed faces of the driver bar and driver.